All about
Woodturning Chucks

What is a woodturning chuck?

It's a device designed to firmly grip one side of your wood blank so that you can turn or hollow the other side, without the need for screws or tailstock support.
It can be a modern multi purpose scroll chuck or as simple as a friction fit or jam-fit chuck made from scrap wood.

Do I need one?

You can turn bowls on a faceplate and hide the screw marks or you can improvise chucks with scrap wood etc but very soon after you start woodturning you will want a scroll chuck because it makes life easier and enables you to do a wider range of projects.

Chucks are useful for the following operations on the lathe :-

• The wood is gripped at one end by the chuck while the other end is being drilled or hollowed out. A good example is the hollowing of the bowl of an eggcup. As the tailstock would get in the way and cannot be used for supporting the end being hollowed, the chuck must have a powerful grip on the end of the wood. Hollowing such items as eggcups, goblets, vase forms and containers with turned lids, when the grain is vertical in the finished piece, is often described as "end grain work".
• Turning bowls. The chuck is used to grip the base of the bowl while the inside is hollowed out. Often the outside of the bowl can be turned at the same time.
• A piece of work, one side of which has been turned in the chuck, is turned around and gripped again, allowing access to the other side and enabling the entire shape to be finished.
  An example is a napkin ring which is first held on the outside so the interior can be hollowed. The second operation is the turning and polishing of the outside. A chuck can be conveniently used for gripping the inside to facilitate this "second operation". If you hear metal machinists talking about doing the "second op." you will now know what the jargon means.

Which type of chuck is the best?

A four jaw self centering scroll chuck with dovetail jaws is the most popular and versatile type.
This Patriot Chuck made in Sheffield, England is typical. It is 100mm diameter overall which is about right for most woodturning lathes. Bigger or smaller chucks are available. It comes with screw-on jaws which are dovetail section inside and out to latch firmly onto the wood and it is easily capable of holding pieces much bigger than the chuck itself. Different sizes and shapes of jaws are available to fit. To enable it to fit every size of lathe thread it has an interchangeable threaded insert to suit your lathe. It even comes with a spanner to quickly change the thread if you have two lathes with different threads or if your lathe has a left and right handed spindle. The Patriot chuck shown here is on sale at Turners Retreat.

How they work

What features are desirable in my new scroll chuck?

• Dovetail jaws. These are shaped to lock onto a turned shaped tenon or spigot to give the strength of a dovetail joint. Engineering style stepped jaws for metal are next to useless for gripping wood.
• The dovetail jaws should also be able to expand and lock into a shaped recess in, say, the base of a bowl.
• Four jaws which self centre - that is they move together inwards or outwards.
• Easy-change jaws. A good range of interchangeable jaws sizes is need for different size projects. Once you have bought your chuck you are committed to one make of chuck accessories and jaws as chucks will only take jaws made by that particular manufacturer. Prices on chuck accessories vary between manufacturers - so look at accessory jaw prices as well as chuck prices before you buy!
• T bar operation. A system of gears preferably enclosed within the chuck enables effortless one handed tightening. Tommy bar operation is a reasonable alternative on budget scroll chucks.
• Interchangeable threaded inserts. If you ever change your lathe you will need to change the thread in the chuck to suit the new lathe spindle.
• Low overhang. A chuck with too much "height" will bring the wood too far away from the bearings causing vibration problems.
• Quality steel. The best chucks have parts made of hardened metal to resist wear on the highly stressed scroll and jaw teeth.
• Indexing holes. This allows you to index the chuck round for drilling or routing jobs - for example a reeded column

Alternative chucks - budget chucks

A good scroll chuck will cost as much as a lathe by the time you have forked out for a wide range of accessory jaws. You might need to economise by using a "collet" chuck
Collet chucks were introduced to provide all the functions needed by woodturners but at around half the price. They usually require you to take them to pieces to change from inside grip to outside grip and the jaw movement is very small so you have to be accurate when you prepare the wood to fit the jaws. However they have a good and accurate grip and will do the job at the cost of speed and convenience.